The subject invention relates to finishing inserts which are used in conjunction with indexable cutting tools. The subject inserts are intended to be used for finishing operations wherein small amounts of material are removed when smoothing machined parts. The finishing insert as disclosed herein represents a modification of the unique cutting insert disclosed in prior copending U.S. application Ser. No. 221,006 filed Dec. 29, 1980, now U.S. Pat. No. 4,359,300 the subject matter of which is incorporated herein by reference.
Indexable cutting tools which are finding wide acceptance in the industry are used in conjunction with replaceable cutting inserts, the latter being formed from a block of abrasion resistant material having a plurality of cutting edges. When a single cutting edge is worn, the insert is rotated to expose a fresh cutting edge such that machining may continue. In a typical machining operation, a workpiece is rotated relative to a cutting tool such that continuous strand portions of the metal workpiece, commonly referred to as chips, are removed in order to form the desired configuration on the workpiece. In finishing operations, relatively thin strands are removed in an effort to produce a smooth surface.
Finishing operations, which are carried out at relatively high speed, light chip load, light feeds, and light depth of cut, produce long chip strands which interfere with the machining of workpiece. More specifically, long chip strands tend to snake out around or over the workpiece thereby abrading the finish which has been carefully smoothed during the earlier phases of the cutting operation. In addition, long strands of metal removed during the operation often pose a safety hazard to the tool operator.
Accordingly, many prior art inserts have been developed which include a configuration which is capable of breaking the chip strands into small pieces thereby obviating the above described problems. More particularly, the inserts include built in chip control grooves which deflect the chips and break them in small pieces. Unfortunately, the configuration of the chip control grooves of the prior art were limited in their application to specific feed rates and depth of cuts. Stated differently, the chip grooves and outer land areas provided on the prior art inserts were only effective when machining at specific depths and feed rates. In the above mentioned copending application, there is disclosed a new and improved insert having chip controlling configuration which may be effectively used in a broad range of cutting depths and feed rates. The insert configurations disclosed in the prior application may be used in conjunction with a variety of standard cutting operations. However, it would be desirable to provide a modified insert configuration which may be used in highly specialized finishing operations wherein lower feed rates and shallower cutting depths are encountered.
Therefore, it is an object of the subject invention to provide a new and improved finishing insert which includes a unique chip groove and central land area configuration which may be utilized to machine finishing cuts throughout a broad range of feed rates and depths.
It is a further object of the subject invention to provide a new and improved cutting insert including a unique chip groove configuration which provides greater chip control at lower feeds, and reduces force and power requirement for a finishing operation thereby increasing metal removal rates per unit of power and reducing temperatures so as to minimize thermal wear and other heat associated problems. Accordingly, longer tool life is achieved.
It is another object of the subject invention to provide a new and improved finishing insert which includes a unique peripheral edge configuration including a V-backed undercut area which is particularly adapted for finishing operations. Furthermore, the unique peripheral edge of the insert of the subject invention employs the benefits of a positive back and side rake angle to further reduce forces, and hence power requirements. Hence, chatter and vibration are effectively reduced or eliminated during a high speed finishing operation.